Smokey BJ74 (1 Viewer)

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Good news guys, havent fired the truck up since I did the fuel filter (about 2 days ago) and its doing wayyy better, should have done it a lot sooner but the Prev Owner said it was just done....it definetly wasnt. The thing weighed a few pounds :censor:
Thanks for all your suggestions and remember to keep up on your maintenence!:cheers:
 
13bt said:
Good news guys, havent fired the truck up since I did the fuel filter (about 2 days ago) and its doing wayyy better, should have done it a lot sooner but the Prev Owner said it was just done....it definetly wasnt. The thing weighed a few pounds :censor:
Thanks for all your suggestions and remember to keep up on your maintenence!:cheers:
Click to expand...

yah!

that was easy and inexpensive for you.

great!
 
13bt said:
Good news guys, havent fired the truck up since I did the fuel filter (about 2 days ago) and its doing wayyy better, should have done it a lot sooner but the Prev Owner said it was just done....it definetly wasnt. The thing weighed a few pounds :censor:
Thanks for all your suggestions and remember to keep up on your maintenence!:cheers:
Click to expand...

So are you saying that replacing your fuel filter appears to have cured your issue with "white and blue exhaust smoke"?

(But then again, if you haven't driven it after changing your filter - How do you know that changing it did anything??? And furthermore, when you say your old filter felt extra-heavy, did you cut it open to see why? )

Questions, questions, question!!! (in my head)

I guess my "regular fuel-filter changes" explains why I have no experience of this filter-smoke connection.

So I wonder what the background-explanation is for fuel-starvation causing a diesel to smoke? All my experience (and I drive poorely-maintained big diesel buses every day) is that it simply causes a lack of power and/or hesitation/jerkiness on steep hills (when fuel demand is highest). :frown:

:cheers:
 
Lostmarbles, the first thing I would check always for black smoke is the air filter or a restricted intake hose (they have collapsed in the past). The first thing for white smoke would be the fuel filter or again a restricted fuel or air leaking into it. I know one of the more common causes for low power and white smoke in the TD4.2 is a small screen on the inlet of the injection pump just under thebanjo fitting. If you didn't know it was there and that it gums up with age, you'd like fork out some $ tro have the pump rebuilt. I suspect that given the rotary pumps on Toyota diesels are the same VE pump design that they too may have this screen. Anyways, once the cheap fixes are ruled out, then one can start digging deeper into the pockets for other fixes/issues like injectors and injector pump.
 
canucksafari said:
Lostmarbles, the first thing I would check always for black smoke is the air filter or a restricted intake hose (they have collapsed in the past).....
Click to expand...

Thanks John

Yes I can understand why excess fuel or lack of air (same thing really) causes black smoke. (I'm assuming there's not enough oxygen to allow proper/efficient combustion.)

.... The first thing for white smoke would be the fuel filter or again a restricted fuel or air leaking into it.I know one of the more common causes for low power and white smoke in the TD4.2 is a small screen on the inlet of the injection pump just under thebanjo fitting. If you didn't know it was there and that it gums up with age, you'd like fork out some $ tro have the pump rebuilt. I suspect that given the rotary pumps on Toyota diesels are the same VE pump design that they too may have this screen............
Click to expand...

This is where I need schooling.

Can you (or anyone else) supply the theory behind this behaviour where less fuel entering the cylinders (from a blockage or air contamination) causes smoke?

I have never experienced this behaviour in the poorly-maintained diesel buses that I drive (at work) or in my BJ40 (which is generally well-maintained). (I've experienced quite a few partially-blocked fuel filters in the buses I drive and power-loss on hills was the thing I noticed .)

If I knew the theory of exactly how "air contamination" or "fuel-flow restriction" causes unburnt fuel (white smoke) to leave the exhaust then I'd be much happier about this. (And if it causes blue smoke - I'd like that explained too. Cos I associate blue smoke with oil-burning.)

I can see that when injectors supply less fuel into cylinders (due to air-contamination or fuel-restriction) less power is produced. But why the smoke?

:cheers:
 
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Just to clear things up, I what I meant in my last post is I just fired the truck up after letting it sit (havent since I did the filter) and now its much better. Just a puff of white when cold starting and a little blue until warm but much better then it was before.

I didnt cut the filter open, the weight compared to the new one was much different, probably over twice as heavy and when I looked inside there was lots of particles floating around the bottom.

My guess on the smoke is a clogged or poorly flowing filter causes a backpressure on the fuel system which in turn may lower injector pressure?? Therefore the atomization on the fuel isnt as complete, giving unburnt fuel after the combustion stroke. Something like that anyways :p
 
13bt said:
Just to clear things up, I what I meant in my last post is I just fired the truck up after letting it sit (havent since I did the filter) and now its much better. Just a puff of white when cold starting and a little blue until warm but much better then it was before. ..
Click to expand...

Thanks for that clarification 13bt. (I misunderstood.)

..I didnt cut the filter open, the weight compared to the new one was much different, probably over twice as heavy and when I looked inside there was lots of particles floating around the bottom....
Click to expand...

Heck! I'd rate "clean fuel" as very important when running a diesel vehicle. (This is the main reason that I've never even considered going down the veggie route.)

If I was you I'd be keen to find the source of that muck. (I suggest flushing out your tank at the very least - assuming you have a drain-plug in its base like I have in mine.)

But I suspect the "smoke" is more likely an issue with some "soluble contaminants" in your "contaminated fuel".

But I also take on board John's (and other people's) comments that have appeared on MUD on this subject - So I'm still in a confused state on this really.

...My guess on the smoke is a clogged or poorly flowing filter causes a backpressure on the fuel system which in turn may lower injector pressure?? Therefore the atomization on the fuel isnt as complete, giving unburnt fuel after the combustion stroke. Something like that anyways :p
Click to expand...

But the injector opening pressure is unchanged! So if that opening-pressure isn't reached, I imagine an injector won't open at all and won't even attempt to atomise the fuel.

(Good idea though! I never considered that!)
 
Out of curiousity, what's the diagnosis behind a flat spot in the acceleration curve?
 
Fuel flow would be my first guess: blocked filter, blocked fuel screen, worn lift pump/injector pump. You need to provide a bit more detail than just "a flat spot".

BTW, I was passed by a 74 on the #1 in Abby today doing between 120 and 125 k. Didn't think they could push big rubber so fast. It began blowing blue at the top of a hill (could smell burnt oil). Thought it was Greg but when I passed it near Aldregrove I saw it was someone else. If it was anyone on MUD, you might want to check it out more closely.
 
My 74 is at Greg's shop - maybe he was out joyriding in it :D
 
canucksafari said:
Fuel flow would be my first guess: blocked filter, blocked fuel screen, worn lift pump/injector pump. You need to provide a bit more detail than just "a flat spot".

BTW, I was passed by a 74 on the #1 in Abby today doing between 120 and 125 k. Didn't think they could push big rubber so fast. It began blowing blue at the top of a hill (could smell burnt oil). Thought it was Greg but when I passed it near Aldregrove I saw it was someone else. If it was anyone on MUD, you might want to check it out more closely.
Click to expand...

I wasn't aware that there was a screen anywhere. Where would that be on a 13BT? I replaced the fuel filter....wasn't that. I am cross posting at this point. There is a dedicated thread to my issue with all the details. https://forum.ih8mud.com/diesel-tech-24-volts-systems/261745-13bt-issues.html
 
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